、、。
To operate a crane, you of course need a license.
Literal
Crane [object-を] operate [for-のには], of-course, license [subject-が] necessary is.
A straightforward factual statement. のには is a composite particle: の nominalizes the verb clause ('operating a crane'), に marks it as the purpose, and は contrasts or topicalizes it. Here it's 'for the purpose of operating a crane, X is needed.' 勿論 ('of course') is slightly more formal in kanji form than in kana (もちろん). 免許 ('license, permit') is the general word for an official license — driving license, crane operator's license, professional certifications. The pattern [goal]には[item]が必要 ('for X, you need Y') is the standard 'necessity for purpose' frame.